1. Field of the Invention
The present invention relates to a power supply control system in a portable data terminal, and more particularly, to a power supply control system of a portable data terminal.
2. Description of the Related Art
Conventionally, a power supply control system for a portable data terminal such as a portable personal computer has been developed to have a small size and to allow the portable data terminal to be possible to operate for a long time.
A drive circuit such as a floppy drive or a compact disk drive is recently provided for a portable personal computer or as an extension unit for the portable personal computer. The required supply capability of a power supply source becomes large with the enhancement of performance of the portable personal computer, so that the large capability power supply source is being developed. In the above case, a conventional small capability power supply source cannot cope with the new portable personal computer with high performance and resources are not effectively utilized.
In conjunction with the above description, a portable personal computer is disclosed in Japanese Patent No. 2648117. In this reference, the portable personal computer includes a plurality of component units with storage units for storing quantities of necessary power of the components units, respectively. An internal battery is provided in the personal computer to supply DC power. In addition, an AC adapter is provided to produce and supply DC power from commercial AC power source. An internal power supply receives the power supplied from the internal battery or the AC adapter and supplies the necessary powers to the component units. A charger performs a charging operation of the internal battery by the power supplied from the AC adapter when an operation instruction signal indicates a charge enable state, and stops the charging operation of the internal battery when the operation instruction signal indicates a charge disable state. A calculating unit collects the quantity of necessary power from each of the storage units of the component units each time a power supply switch is turned on or a system configuration of the portable personal computer s changed, and calculates a total quantity of necessary power. A comparator compares the total quantity of necessary power and a first quantity of power P1. Then, the comparator supplies the operation instruction signal indicating the charge enable state to the charger when the total quantity of necessary power is less than the first quantity of power P1, and the operation instruction signal indicating the charge disable state to the charger when the total quantity of necessary power is larger than the first quantity of power P1.
Therefore, an object of the present invention is to provide a power supply control system in a portable data terminal which can control the operations of function components of the portable data terminal based on the power supply capability of a power supply source.
In order to achieve an aspect of the present invention, a data terminal apparatus includes a basic unit, a plurality of units, a power supply circuit, switching units and a controller. The basic unit realizes a basic function of the data terminal apparatus and requires a basic quantity of DC power. Each of the plurality of units realizes a specific function of the data terminal apparatus and requires quantities of DC power. The power supply circuit receives DC power from a power supply source, and can supply the DC power to the basic unit and the plurality of units. The switching units are provided for the plurality of units, and each of the switching units selectively supplies the DC power from the power supply circuit to a corresponding one of the plurality of units in response to a switching control signal. The controller selectively outputs the switching control signals to the switching units based on the DC power of the power supply source.
Here, the power supply source may be one of an AC adapter producing the DC power from an AC power and a battery. In this case, the power supply source has a specific data. The data terminal apparatus further includes an interface unit with which the power supply source is connected and which supplies the DC power from the power supply source to the power supply circuit. The controller reads the specific data from the power supply source through the interface unit and selectively outputs the switching control signals to the switching units based on the specific data. Also, the controller ay include a first table and a second table. The first table stores sets of a power indication data and the specific data. The second table stores a necessary power quantity of the basic unit, and a necessary power quantity of each of the plurality of units. The controller refers to the first table to determine the power indication data, and selectively outputs the switching control signals to the switching units based on the power indication data and the necessary power quantity of the basic unit, and the necessary power quantity of each of the plurality of units.
The controller may dynamically selectively output the switching control signals to the switching units based on the DC power of the power supply source.
Also, the plurality of units are input/output units.
In addition, the controller may output one of a switching ON signal and a switching OFF signal to each of the plurality of units based on the Dc power of the power supply source. Each of the switching units supplies the DC power to a corresponding one of the plurality of units in response to the switching ON signal and stops the supply of the DC power to the corresponding one of the plurality of units in response to the switching OFF signal.
In order to achieve another aspect of the present invention, a method of controlling power supply in a data terminal apparatus, includes:
determining a quantity of DC power which can be supplied;
supplying the DC power to a basic unit of the data terminal apparatus; and
selectively supplying the DC power to each of input/output units based on the determined quantity of DC power.
The quantity of DC power which can be supplied, may be supplied from an external power supply source.
Also, when the quantity of DC power which can be supplied is supplied from an external power supply source, the determining includes:
reading a specific data from the power supply source; and
determining the quantity of DC power which can be supplied control, based on the specific data.
Also, the selectively supplying may include:
selectively supplying the DC power to each of input/output units based on the determined quantity of DC power and a necessary power quantity of each of the input/output units.
In addition, the selectively supplying may include:
dynamically selectively the DC power to each of input/output units based on the determined quantity of DC power and a necessary power quantity of each of the input/output units.